scholarly journals Transient Parameter Analysis of Non-scrammed Local Melting Accidents—A VVER 1000 Case Study

2021 ◽  
Vol 9 ◽  
Author(s):  
Behzad Salmassian ◽  
Ataollah Rabiee ◽  
Mohammad R. Nematollahi ◽  
Farshad Faghihi ◽  
Ahmad Pirouzmand
Keyword(s):  
Void Fraction ◽  
Nuclear Power ◽  
Transient Analysis ◽  
Parameter Analysis ◽  
Pump Failure ◽  
Power Increase ◽  
Weak Points ◽  
Uncertainty Analyses ◽  
Flow Blockage

The first stage of a core degradation—based on the defense-in-depth concept of nuclear power plant (NPP) safety—is prone to fuel melting due to local blockage. The flow blockage accidents with no SCRAM happening can lead to a local fuel-clad failure, consequently affecting the safety of NPP. The present study provides an analysis of Anticipated Transient Without SCRAM (ATWS), which might lead to a condition of burning out. The accidents related to the ATWS scenarios, detailed in the case of VVER-1000/V446 reactor FSAR (Final Safety Analysis Report), include pump failure, local blockage, relative power increase, and a combination of these transients. In this research, first, drawing upon MCNPX 2.7 and COBRA-EN codes, a coupling framework is developed and then validated using an authentic reference point. The obtained results reveal that the reactor SCRAM does not occur while accidents are being investigated as there is a 10% difference in the mass flow rate reduction, a 470 kPa in the channel pressure drop, and a 204°K in the clad temperature, which constitute limitations under most pessimistic scenarios. However, under these conditions, a 70% void fraction over 12 min is observed in certain channels. Hence, burnout and local fuel melting could occur under normal operational and ATWS circumstances. According to uncertainty analyses, the occurrence of the void fraction above zero is locally definite. The transient analysis outputs could be deployed as monitoring system inputs and exploited for identifying weak points in the system.

scholarly journals Transient Analysis of Heat Transfer Across the Residential Building Roof with Pcm and Wood Wool- A Case Study by Numerical Simulation Approach

2013 ◽  
Vol 59 (4) ◽  
pp. 483-497 ◽  
Author(s):  
D. Prakash ◽  
P. Ravikumar
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Phase Change ◽  
Phase Change Material ◽  
Transient Analysis ◽  
Residential Building ◽  
Building Roof ◽  
Type 3 ◽  
Change Material

Abstract In this paper, transient analysis on heat transfer across the residential building roof having various materials like wood wool, phase change material and weathering tile is performed by numerical simulation technique. 2-dimensional roof model is created, checked for grid independency and validated with the experimental results. Three different roof structures are included in this study namely roof with (i). Concrete and weathering tile, (ii). Concrete, phase change material and weathering tile and (iii). Concrete, phase change material, wood wool and weathering tile. Roof type 3 restricts 13% of heat entering the room in comparison with roof having only concrete and weathering tile. Also the effect of various roof layers’ thickness in the roof type 3 is investigated and identified that the wood wool plays the major role in arresting the entry of heat in to the room. The average reduction of heat is about 10 % for an increase of a unit thickness of wood wool layer.

scholarly journals HEIGHT DETERMINATION TECHNIQUES FOR THE NEXT NATIONAL HEIGHT SYSTEM OF FINLAND - A CASE STUDY

2015 ◽  
Vol 41 (4) ◽  
pp. 145-155
Author(s):  
Timo Saari ◽  
Markku Poutanen ◽  
Veikko Saaranen ◽  
Harri Kaartinen ◽  
Antero Kukko ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Pilot Project ◽  
Satellite System ◽  
Reference Station ◽  
Virtual Reference ◽  
Precise Levelling ◽  
Height Determination ◽  
Weak Points ◽  
Global Navigation Satellite

Precise levelling is known for its accuracy and reliability in height determination, but the process itself is slow, laborious and expensive. We have started a project to study methods for height determination that could decrease the creation time of national height systems without losing the accuracy and reliability that is needed for them. In the pilot project described here, we study some of the alternative techniques with a pilot field test where we compared them with the precise levelling. The purpose of the test is not to evaluate the mutual superiority or suitability of the techniques, but to establish the background for a larger test and to find strong and weak points of each technique. The techniques chosen for this study were precise levelling, Mobile Laser Scanning (MLS) and Global Navigation Satellite System (GNSS) levelling, which included static Global Positioning System (GPS) and Virtual Reference Station (VRS) measurements. This research highlighted the differences of the studied techniques and gave insights about the framework and procedure for the later experiments. The research will continue in a larger scale, where the suitability of the techniques regarding the height systems is to be determined.

Probabilistic Analysis by Applying Uncertainty Worflows: A Case Study of the Teak Field, East Coast Trinidad

2014 ◽  
Author(s):  
C.J.. J. Segnini ◽  
M.. Rashwan ◽  
M.J.. J. Hernandez ◽  
J. A. Rojas ◽  
M.A.. A. Infante
Keyword(s):  
Reservoir Simulation ◽  
Probabilistic Analysis ◽  
East Coast ◽  
Dynamic Properties ◽  
Large Population ◽  
Model Performance ◽  
Current Standard ◽  
Modeling Software ◽  
Uncertainty Analyses

Abstract This paper presents a methodology for the probabilistic analysis of an infill or step-out opportunity using numerical simulation. Sensitivity and uncertainty analyses for all involved parameters were evaluated through different experimental design techniques. Subsequently, a proxy model was established to reproduce the numerical model performance. Finally, three appropriate solutions were selected from a large population of realizations corresponding to probabilistic percentiles (90%, 50%, and 10% certainty that the specified volume will be recovered). This proposed methodology helped the asset team to evaluate the well candidates more precisely, confidently, and in less time than the current standard methodology. More knowledge about the variables and their effects on overall outcomes was also gained, which helped the team make more-informed decisions. The workflow used the same numerical modeling software, incorporating and facilitating the changes of both static and dynamic properties simultaneously. A case study from Teak field, on the east coast of Trinidad, illustrates the applicability of the methodology and compares its results to those obtained using the standard workflow for the asset. The methodology is one of the latest developments in reservoir simulation, and it has not yet been incorporated into the operator's common practices and procedures for exploitation of the TSP fields.

Verification of Plastic Interactive Systems

i-com ◽  
2015 ◽  
Vol 14 (3) ◽  
Author(s):  
Raquel Oliveira ◽  
Sophie Dupuy-Chessa ◽  
Gaëlle Calvary
Keyword(s):  
Power Plant ◽  
User Interfaces ◽  
Nuclear Power ◽  
Interactive Systems ◽  
System Model ◽  
Equivalence Checking ◽  
The Past ◽  
Different Levels ◽  
Formal Techniques

AbstractInteractive systems have largely evolved over the past years. Nowadays, different users can interact with systems on different devices and in different environments. The user interfaces (UIs) are expected to cope with such variety. Plastic UIs have the capacity to adapt to changes in their context of use while preserving usability. Such capability enhances UIs, however, it adds complexity on them. We propose an approach to verifying interactive systems considering this adaptation capability of the UIs. The approach applies two formal techniques: model checking, to the verification of properties over the system model, and equivalence checking, to compare different versions of a UI, thereby identifying different levels of UI equivalence. We apply the approach to a case study in the nuclear power plant domain in which several UI are analyzed, properties are verified, and the level of equivalence between them is demonstrated.

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